Correction: Polymeric hole-transport materials with side-chain redox-active groups for perovskite solar cells with good reproducibility.

Correction for 'Polymeric hole-transport materials with side-chain redox-active groups for perovskite solar cells with good reproducibility' by Rosinda Fuentes Pineda et al., Phys. Chem. Chem. Phys., 2018, 20, 25738-25745.

Polymeric hole-transport materials with side-chain redox-active groups for perovskite solar cells with good reproducibility.

Two monomers, M:OO and M:ON, and their corresponding polymers, P:OO and P:ON, were prepared from styrene derivatives N,N-diphenyl-4-vinyl-aniline with different substituents (-OCH3 and -N(CH3)2) in the N-phenyl para positions. The polymers were synthesised and fully characterised to study their function as hole transport materials (HTMs) in perovskite solar cells (PSCs). The thermal, optical and electrochemical properties and performance of these monomers and polymers as HTMs in PSCs were compared in terms of their structure. The polymers form more stable amorphous glassy states and showed higher thermal stability than the monomers. The different substituent in the para position influenced the highest occupied molecular orbital (HOMO) level, altering the oxidation potential. Both monomers and polymers were employed as HTMs in perovskite solar cells with a device configuration FTO/bl-TiO2/mp-TiO2/CH3NH3PbI3/HTM/Au resulting in power conversion efficiencies of 7.48% for M:OO, 5.14% for P:OO, 5.28% for P:ON and 3.52% for M:ON. Although showing comparatively low efficiencies, the polymers showed much superior reproducibility in comparison with Spiro-OMeTAD or the monomers, suggesting further optimisation of polymeric HTMs with redox side groups is warranted.

Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging.

The accumulation of irreparable cellular damage restricts healthspan after acute stress or natural aging. Senescent cells are thought to impair tissue function, and their genetic clearance can delay features of aging. Identifying how senescent cells avoid apoptosis allows for the prospective design of anti-senescence compounds to address whether homeostasis can also be restored. Here, we identify FOXO4 as a pivot in senescent cell viability. We designed a FOXO4 peptide that perturbs the FOXO4 interaction with p53. In senescent cells, this selectively causes p53 nuclear exclusion and cell-intrinsic apoptosis. Under conditions where it was well tolerated in vivo, this FOXO4 peptide neutralized doxorubicin-induced chemotoxicity. Moreover, it restored fitness, fur density, and renal function in both fast aging XpdTTD/TTD and naturally aged mice. Thus, therapeutic targeting of senescent cells is feasible under conditions where loss of health has already occurred, and in doing so tissue homeostasis can effectively be restored.

Iron(ii) ß-ketiminate complexes as mediators of controlled radical polymerisation.

A series of tridentate, ONO- and ONN-chelating ß-ketiminate ligands were synthesised via condensation reactions, and complexed with iron(ii) using [Fe(N(SiMe3)2)2THF]. The complexation reactions proceeded in high yields to generate novel, monomeric, tetracoordinate iron(ii) complexes, each bearing a bis(trimethylsilyl)amide ligand, as confirmed by X-ray crystallography. These complexes were amenable to further reaction (protonolysis) with alcohols and phenols, generating alkoxide/phenolate-containing complexes that were dimeric in the solid state. All complexes synthesised were screened as potential mediators of the controlled radical polymerisation (CRP) of styrene and methyl methacrylate under both atom transfer radical polymerisation (ATRP) and organometallic mediated radical polymerisation (OMRP) conditions. Whilst all of the complexes were relatively poor ATRP mediators under the conditions used here, regardless of monomer choice, dispersities (D) as low as 1.58 for styrene and 1.23 for methyl methacylate polymerisation under OMRP conditions could be achieved. The better performance in methacrylate polymerisation suggests the formation of a stronger metal-carbon bond in these systems. In particular, the use of a ß-ketiminate ligand functionalised with an N,N-dimethylethylene pendant arm and a 2,6-diphenylphenolate ligand affords a potential Fe-based mediator of methyl methacrylate OMRP.

Solid-state structure, solution-state behaviour and catalytic activity of electronically divergent C,N-chelating palladium-N-heterocyclic carbene complexes.

A family of electronically diverse pyridyl- and picolyl-substituted imidazolium salts have been prepared and coordinated to palladium in a single step, to deliver a variety of palladium(ii)-N-heterocyclic carbene (NHC) complexes. Neutral Pd(NHC)X2, cationic [Pd(NHC)2X]X and dicationic [Pd(NHC)2]X2-type complexes have been isolated and fully characterised, with single-crystal X-ray analysis revealing a variety of coordination environments around the palladium centres. The pre-formed complexes have been employed in a model Suzuki-Miyaura cross-coupling reaction to yield a sterically congested tetra-ortho-substituted biaryl product, showcasing turnover numbers comparable to Pd-PEPPSI-IPr catalyst.

Synthesis and anticancer activity of silver(I)-N-heterocyclic carbene complexes derived from the natural xanthine products caffeine, theophylline and theobromine.

A new library of silver(I)-N-heterocyclic carbene complexes prepared from the natural products caffeine, theophylline and theobromine is reported. The complexes have been fully characterised using a combination of NMR spectroscopy, mass spectrometry, elemental analysis and X-ray diffraction analysis. Furthermore, the hydrophobicity of the complexes has been measured. The silver(I)-N-heterocyclic carbenes have been evaluated for their antiproliferative properties against a range of cancer cell lines of different histological types, and compared to cisplatin. The data shows different profiles of response when compared to cisplatin in the same panel of cells, indicating a different mechanism of action. Furthermore, it appears that the steric effect of the ligand and the hydrophobicity of the complex both play a role in the chemosensitivity of these compounds, with greater steric bulk and greater hydrophilicity delivering higher cytotoxicity.

Mechanistic insights into the oxidative coupling of N-heterocyclic carbenes within the coordination sphere of copper complexes.

The behavior of N-heterocyclic carbene (NHC) ligands in organometallic chemistry is hugely important for catalysis, due to the effect of these ligands on catalytic pathways and their involvement in catalyst decomposition. In this report, a combined experimental and computational study is presented, which provides mechanistic understanding of the unprecedented oxidative coupling of NHCs at Cu. The presence of Cu(I) -, Cu(II) -, and Cu(III) -NHC complexes during the process is postulated, with the unusual Ccarbene -Ccarbene oxidative coupling reaction occurring under extremely mild reaction conditions. This process may represent a novel pathway for the decomposition of Cu-NHC complexes.

Structural diversity of copper(I)-N-heterocyclic carbene complexes; ligand tuning facilitates isolation of the first structurally characterised copper(I)-NHC containing a copper(I)-alkene interaction.

The preparation of a series of imidazolium salts bearing N-allyl substituents, and a range of substituents on the second nitrogen atom that have varying electronic and steric properties, is reported. The ligands have been coordinated to a copper(I) centre and the resulting copper(I)-NHC (NHC=N-heterocyclic carbene) complexes have been thoroughly examined, both in solution and in the solid-state. The solid-state structures are highly diverse and exhibit a range of unusual geometries and cuprophilic interactions. The first structurally characterised copper(I)-NHC complex containing a copper(I)-alkene interaction is reported. An N-pyridyl substituent, which forms a dative bond with the copper(I) centre, stabilises an interaction between the metal centre and the allyl substituent of a neighbouring ligand, to form a 1D coordination polymer. The stabilisation is attributed to the pyridyl substituent increasing the electron density at the copper(I) centre, and thus enhancing the metal(d)-to-alkene(π*) back-bonding. In addition, components other than charge transfer appear to have a role in copper(I)-alkene stabilisation because further increases in the Lewis basicity of the ligand disfavours copper(I)-alkene binding.

Simple and versatile selective synthesis of neutral and cationic copper(I) N-heterocyclic carbene complexes using an electrochemical procedure.

An electrochemical approach for the preparation of copper(I) N-heterocyclic carbene complexes has been developed to include a diverse range of ligand precursors. Importantly, the method is effective for a ligand precursor that contains several acidic protons and for which traditional methods of carbene formation are not suitable.

Demyelinating diseases: myeloperoxidase as an imaging biomarker and therapeutic target.

PURPOSE: To evaluate myeloperoxidase (MPO) as a newer therapeutic target and bis-5-hydroxytryptamide-diethylenetriaminepentaacetate-gadolinium (Gd) (MPO-Gd) as an imaging biomarker for demyelinating diseases such as multiple sclerosis (MS) by using experimental autoimmune encephalomyelitis (EAE), a murine model of MS. MATERIALS AND METHODS: Animal experiments were approved by the institutional animal care committee. EAE was induced in SJL mice by using proteolipid protein (PLP), and mice were treated with either 4-aminobenzoic acid hydrazide (ABAH), 40 mg/kg injected intraperitoneally, an irreversible inhibitor of MPO, or saline as control, and followed up to day 40 after induction. In another group of SJL mice, induction was performed without PLP as shams. The mice were imaged by using MPO-Gd to track changes in MPO activity noninvasively. Imaging results were corroborated by enzymatic assays, flow cytometry, and histopathologic analyses. Significance was computed by using the t test or Mann-Whitney U test. RESULTS: There was a 2.5-fold increase in myeloid cell infiltration in the brain (P = .026), with a concomitant increase in brain MPO level (P = .0087). Inhibiting MPO activity with ABAH resulted in decrease in MPO-Gd-positive lesion volume (P = .012), number (P = .009), and enhancement intensity (P = .03) at MR imaging, reflecting lower local MPO activity (P = .03), compared with controls. MPO inhibition was accompanied by decreased demyelination (P = .01) and lower inflammatory cell recruitment in the brain (P < .0001), suggesting a central MPO role in inflammatory demyelination. Clinically, MPO inhibition significantly reduced the severity of clinical symptoms (P = .0001) and improved survival (P = .0051) in mice with EAE. CONCLUSION: MPO may be a key mediator of myeloid inflammation and tissue damage in EAE. Therefore, MPO could represent a promising therapeutic target, as well as an imaging biomarker, for demyelinating diseases and potentially for other diseases in which MPO is implicated.

Extent and organization of opossum prefrontal cortex defined by anterograde and retrograde transport methods.

Prefrontal cortex is commonly defined as cortex which receives afferents from the thalamic mediodorsal nucleus (MD). The extent of opossum prefrontal cortex was mapped with anterograde and retrograde axonal transport methods. The prefrontal field was found to include not only cortex on the lateral convexity of the frontal lobe as reported in earlier studies, but, in addition, cortex within the rhinal fissure and cortex on the rostral medial wall of the hemisphere. The organization of the thalamic input to the medial wall was analyzed in some detail and compared with that of the rat. The reason for this emphasis stemmed from earlier observations which suggested that a lateral, nonolfactory segment of MD, prominent in the rat and other species, may not be present in opossum MD. In the rat, the lateral segment, which constitutes approximately one-third of MD, projects to a relatively large expanse of rostral medial cortex which is also projected upon by the anteromedial nucleus. The main projection field of the lateral one-third of opossum MD is to cortex on the lateral convexity of the frontal lobe which has no input from the anteromedial nucleus and has no counterpart in the rat. Only the most lateral edge of opossum MD projects to medial cortex, to a very small field, which is also projected upon by the anteromedial nucleus. In other respects, the organization of the rostral medial cortex is similar in rat and opossum. These results suggest that, rather than being absent, an equivalent of a nonolfactory segment may be present in opossum MD but is markedly reduced in size, compared to that in rat and other species.

Effects of stimulation of the mediodorsal nucleus and its projection cortex on heart rate in the rabbit.

Electrical stimulation of prefrontal cortex in anesthetized rabbits evoked small (less than 10%) changes in heart rate. In contrast, stimulation of the thalamic mediodorsal nucleus (MD) elicited decreases in heart rate proportional to the stimulating current. The maximal peak reductions in heart rate evoked by higher current intensities were 85% from prestimulus levels. The bradycardiac response had a short latency after stimulus onset (less than 1 s, peak within 5 s), and the heart rate usually returned to baseline within 30 s after stimulation. Vagal cholinergic innervation of the heart was suggested as the final effector pathway since bilateral vagotomy or administration of atropine (sulfate or methyl nitrate, 0.15-0.4 mg/kg, i.v.) virtually abolished the rapid bradycardiac responses. Administration of a beta-adrenergic receptor blocker (propranolol, 3 mg/kg, i.v.) was without effect on the heart rate response. The effective medial thalamic area for evoking a response was localized to MD, the thalamic midline nuclei between both MDs and a region continuous with, but posterior to MD (e.g. parafascicular nucleus). A descending effector pathway from the thalamus was implicated since complete bilateral ablation of prefrontal cortex did not reduce the stimulus-produced bradycardia evoked from MD. Similar large bradycardiac responses were obtained in an unanesthetized preparation to both MD stimulation and to sensory stimuli, suggesting a possible physiological correlate for these intracranially-evoked heart rate changes.

Sources of olfactory inputs to opossum mediodorsal nucleus identified by horseradish peroxidase and autoradiographic methods.

Some sources of olfactory input to the opossum mediodorsal thalamic nucleus (MD) were identified by retrograde horseradish peroxidase and anterograde autoradiographic methods. One major source originated from the olfactory tubercle and a narrow strip of piriform cortex bordering the tubercle. The tubercle-MD projection exhibited a definite spatial organization and included all except the most medial part of MD. The fact that the projection reached the most lateral and ventral extent of MD abutting the intralaminar complex suggests that the entire opossum MD may correspond to only the medial, magnocellular division in the primate and that the equivalents of both the parvocellular and paralamellar divisions may be absent.

Cortical projections of the thalamic mediodorsal nucleus in the rabbit.

The cortical projection of the thalamic mediodorsal nuclear complex (MD) in the rabbit was mapped retrograde horseradish peroxidase and anterograde tritiated proline techniques. The projection field occupied the entire medial wall rostral to a mid corpus callosal level, wrapped around the frontal pole onto the lateral convexity and tailed off caudally on the dorsal bank of the rhinal sulcus. The projection of the lateral approximately one-half of MD, the half which does not receive olfactory input, was confined to medial cortex supply all but the most rostral region. This projection field of lateral MD was precisely organized in two dimensions with the most lateral part projecting most caudally and the most dorsal part projecting most ventrally. A representation for the third, anterior-posterior (A-P), dimension was not evident since any cortical point within the field was supplied by a cylinder of cells extending the entire A-P extent of lateral MD. The medial half of MD, which does receive olfactory input, projected to the remaining rostral medical cortex, the lateral convexity and rhinal sulcal region. The inverse dorsoventral relationship was partially preserved and on overlapping A-P gradient was present with sulcal projections originating more caudally in medial MD and the rostral medial projection originating more rostrally.

The distribution of olfactory input in the opossum mediodorsal nucleus.

Discharges of single cells in the thalamic mediodorsal nucleus (MD) of the opossum were recorded during electrical stimulation of the lateral olfactory tract. Responsive sites were histologically localized throughout the entire mediolateral extent of MD. In both rabbit and squirrel monkey responses are confined to the medial half of MD. Thus the lateral non-olfactory nuclear subdivision, common to both rabbit and squirrel monkey, was not found in the opossum. Firing patterns of cells were similar to those observed in rabbit and squirrel monkey. They commonly consisted of an early spike or burst of spikes, followed by a period of inactivity and then, in many cells, by a later period of response or of resumed spontaneous activity. The results indicate that olfactory input is characteristic of MD in a diverse sample of mammals but that topographic organization of the input is distinctly different in the opossum.